As an electronic apparatus such as an electronic timepiece having a function for receiving wireless information, there is known, for example, a radio wave clock for receiving time information wirelessly transmitted (standard radio waves) and performing time correction. Such a radio wave clock is normally driven by battery, but since power is consumed by radio wave reception, the lifetime of the battery is shorter than a normal clock, there is a problem that the battery should be replaced very often.
Because of this, a radio wave clock having a solar power-generation mechanism installed as a power-generation mechanism is known (for example, Japanese Unexamined Patent Application Publication No. 11-160464).
The radio wave clock having a solar power-generation mechanism includes a solar battery as a solar power-generation mechanism, a receiving mechanism having an antenna for receiving time information, and a time-measuring mechanism for measuring time, the time of the time-measuring mechanism being corrected according to the time information received by the antenna.
By such a structure, the time-measuring mechanism and the receiving mechanism can be driven by using the power generated by the solar power generation. Therefore, only if the solar battery generates and charges from solar light, the clock having a solar power-generation mechanism can be used as a radio wave clock driven semi-permanently.
However, there is a problem in a solar power-generation mechanism that it does not always efficiently operate according to daylight amount (for example, cloudy or rainy weather), seasons (for example, winter), regions (for example, high latitude region), etc., so that it sometimes cannot supply power. The radio wave clock needs a large amount of power since the received time information should be processed (amplification, demodulation) by the receiving mechanism. Because of this, if sufficient power is not supplied to the receiving mechanism, time information cannot be received, or wrong time information is received, the receiving sensitivity of the receiving mechanism is decreased. Further, there is also a problem that a rapid charge is impossible in the solar battery if light is weak.
Because of this, the radio wave clock having the solar power-generation mechanism is not necessarily a convenient clock.
Therefore, the inventor of the present invention studied a method of incorporating a power-generation mechanism using a rotary weight inside the radio wave clock. The power-generation mechanism using a rotary weight includes a rotary weight rotatably installed, and a generator for converting the mechanical energy by the rotary weight to electrical energy, and a rotor of the generator is rotated by the rotary weight, and power generation occurs in a power-generation coil by the change of magnetic flux accompanied by the rotation. By such a structure, power can be generated, for example, by wearing the electronic timepiece in which the power-generation mechanism is installed on an arm, and moving the rotary weight. Therefore, compared with the solar power generation, the power generation by using the rotary weight is possible regardless of seasons, daylight amount, etc., and also has an advantage that much faster power generation can be easily performed.
However, the rotary weight needs to have sufficient moment of inertia to make sufficient energy by the movement of the rotary weight. Because of this, as a material of the rotary weight, a metal of high weight (heavy metal) such as tungsten alloy or gold alloy is normally used. If the power-generation mechanism by such a rotary weight is simply installed in the radio wave clock, the conductive rotary weight of a metal material shields the time information to be received by the antenna. Therefore, there occurs a new problem that the standard radio waves cannot be received if the power-generation mechanism using the rotary weight is installed in the radio wave clock.
Such a problem is not limited to an electronic timepiece having a radio wave correction function, and it is a common problem in various electronic apparatus having a power-generation mechanism by a rotary weight, and an antenna receiving wireless information from the outside.
The object of the present invention is to solve the above problems, and to provide an electronic timepiece and an electronic apparatus which can generate electricity by a power-generation mechanism having a rotary weight, and can receive wireless information.